Metal tooth detection and locating

ABSTRACT

Methods and systems for tracking heavy machine teeth. One system includes a heavy machine tooth configured to be mounted on a bucket of a heavy machine, an active RFID tag coupled to the heavy machine tooth to move with the tooth, and an RFID reader configured to read data from the RFID tag, The RFID reader is further configured to provide an indication regarding the location of the tooth when the tooth separates from the bucket based on the data read from the RFID tag and provide diagnostic information regarding the heavy machine tooth based on the data read from the RFID tag.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/517,479, filed Oct. 17, 2014, which is a continuation of U.S.application Ser. No. 13/220,260, filed Aug. 29, 2011. The entire contentof both prior-filed applications is hereby incorporated by reference.

BACKGROUND

The invention relates to detection and locating of heavy machine teeth,specifically the use of radio frequency identification (RFID) tags todetermine when a metal tooth is no longer on a bucket of a heavymachine.

Heavy machines (e.g., mining equipment such as draglines and shovels)utilize steel teeth in their bucket designs. The teeth are used forseveral reasons: They provide a smaller point of surface area whendigging into the earth, helping to break up the earth, and requiringless force than the larger surface area of a bucket itself In addition,the teeth provide easily replaceable wear points that save the bucketitself from wearing down. However, as a tooth wears down, there iscurrently no method to measure wear without physically removing thetooth.

When the teeth wear down, they typically fall off. The current method ofdetecting when a tooth falls off is an expensive machine vision systemthat looks at the bucket and detects when a tooth has gone missing. Thissystem is extremely costly to implement, and only lets the operator knowthat the tooth has gone missing, not where it is. Once a crew notices atooth is missing, they haul away an average ten truckloads of materialin hopes of locating and separating out the fallen tooth. If they areunable to locate the tooth, the tooth can end up in a crusher. Inaddition the tooth can become stuck in the crusher and be ejected fromthe crusher, potentially harming other equipment.

SUMMARY

In one embodiment, the invention provides a method of monitoring a heavymachine tooth. The method includes coupling an RFID tag to the heavymachine tooth and positioning an RFID reader to read the RFID tag. TheRFID reader provides an indication that the heavy machine tooth isseparated from the heavy machine.

In other embodiments, the invention provides a heavy machine toothmonitoring system that includes a heavy machine tooth configured to bemounted on a bucket of a heavy machine, an active RFID tag coupled tothe tooth, and an RFID reader configured to read data from the RFID tag.

In yet another embodiment, the invention provides a method of monitoringa heavy machine tooth. The method includes coupling an RFID tag to theheavy machine tooth, the RFID tag coupled to the heavy machine tooth tomove with the heavy machine tooth and positioning an RFID reader to readthe RFID tag. The method also includes receiving, by a controller,information from the RFID reader based on the data from the RFID tag,determining, by the controller, when the heavy machine tooth isseparated from the heavy machine based on the information from the RFIDreader, and determining, by the controller, diagnostic information forthe heavy machine tooth based on the information from the RFID reader.In addition, the method includes providing, to a user, the diagnosticinformation and an indication to a user when the heavy machine tooth isseparated from the heavy machine.

In still a further embodiment, the invention provides a heavy machinetooth monitoring system. The system includes a heavy machine toothconfigured to be mounted on a bucket of a heavy machine, an active RFIDtag coupled to the heavy machine tooth to move with the tooth, and anRFID reader configured to read data from the RFID tag, The RFID readeris further configured to provide an indication regarding the location ofthe tooth when the tooth separates from the bucket based on the dataread from the RFID tag and provide diagnostic information regarding theheavy machine tooth based on the data read from the RFID tag.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an exemplary shovel.

FIGS. 2A and 2B illustrate the operation of an exemplary mining site.

FIG. 3 is an exploded view of a construction of a bucket toothincorporating an RFID tag.

FIG. 4 is another view of the bucket tooth of FIG. 3.

FIG. 5 is a cut-away view of the bucket tooth of FIG. 3.

FIG. 6 is a plan view of another construction of a bucket toothincorporating an RFID tag.

FIG. 7 is a plurality of views of a third construction of a bucket toothincorporating an RFID tag.

FIG. 8 is a plan view of a construction of a ceramic plug for insertingan RFID tag into the bucket tooth of FIG. 7.

FIG. 9 is a schematic diagram of a wear detection circuit.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways.

Heavy machines are used to move large amounts of earth in industriessuch as mining and construction. Some heavy machines (e.g., an electricshovel) include buckets for scooping up the earth. The buckets ofteninclude a plurality of teeth to help break up the earth, and make iteasier to scoop the earth into the bucket.

FIG. 1 shows an exemplary electric shovel 100 used for surface miningapplications. The electric shovel 100 includes a mobile base 105supported on drive tracks 110. The mobile base 105 supports a turntable115, and a machinery deck 120. The turntable 115 permits full 360°rotation of the machinery deck 120 relative to the base 105.

A boom 125 is pivotally connected at 130 to the machinery deck 120. Theboom 125 is held in an upwardly and outwardly extending relation to thedeck by a brace or gantry in the form of tension cables 135 which areanchored to a back stay 140 of a stay structure 145 rigidly mounted onthe machinery deck 120.

A dipper or bucket 150 includes a plurality of teeth 152, and issuspended by a flexible hoist rope or cable 155 from a pulley or sheave160, the hoist rope is anchored to a winch drum 165 mounted on themachinery deck 120. As the winch drum rotates, the hoist rope 155 iseither paid out or pulled in, lowering or raising the dipper 150. Theboom pulley 160 directs the tension in the hoist rope 155 to pullstraight upward on the shovel dipper 150 thereby producing efficient digforce with which to excavate the bank of material. The dipper 150 an armor handle 170 rigidly attached thereto, with the dipper arm 170slideably supported in a saddle block 175, which is pivotally mounted onthe boom 125 at 180. The dipper arm 170 has a rack tooth formationthereon (not shown) which engages a drive pinion or shipper shaft (notshown) mounted in the saddle block 175. The drive pinion is driven by anelectric motor and transmission unit 185 to effect extension orretraction of the dipper arm 170 relative to the saddle block 175.

The shovel boom 125 is a major structural component in size, shape, andweight. Its main purpose is to hold the boom pulley 160 in anadvantageous position for efficient hoist dipper pull through the bank.Another major purpose of the boom 125 is to mount the shipper shaft at asufficient height and outward radius from the centerline of rotation ofthe shovel 100. The shipper shaft powers the shovel handle to extend andretract the dipper 150. These two features of an electric shovel diggingattachment make the shovel uniquely qualified to reach and dig high bankformations safely away from the shovel. The shovel in this regard isalso able to reach a great volume of material in one sitting withoutpropelling closer to the bank.

The bucket teeth 152 are removably attached to the bucket 150. Thisenables broken or worn teeth 152 to be easily replaced. However, thisleads to teeth 152 occasionally breaking or falling off of the bucket150. In some circumstances, a tooth 152 will break/fall off the bucket150 and end up in the earth being mined (i.e., in the bucket 150). Whenthe earth in the bucket 150 is deposited in a truck, the tooth 152 goesinto the truck as well. Often the earth in the truck is taken to acrusher to be crushed. When the truck empties its contents into thecrusher, the tooth 152 goes into the crusher as well, potentiallydamaging the crusher, being expelled from the crusher and damaging otherequipment, or being damaged in the crusher.

FIGS. 2A and 2B represent a typical mining operation. The shovel 100digs up earth 200 with its bucket 150, and dumps the earth 200 into atruck 205. Once the truck 205 is full, the truck 205 takes the earth 200to another location (e.g., at the mining site or remote from the miningsite). In some operations, the truck 205 takes the earth 200 to acrusher 210. The truck 205 deposits the earth 200 onto a conveyor 215which feeds the earth 200 into the crusher 210 which crushes the earth200 into smaller components 220.

The invention uses an active RFID tag embedded in or attached to themetal tooth 152 of the heavy machine bucket to enable detection of atooth 152 missing from the bucket 150.

The invention uses an RFID reader 225 located on a structure (e.g., anexit gate) through which the truck 205 passes after being filled. TheRFID reader 225 checks if an RFID tag passed near the structure. If anRFID tag is detected, an alarm can be triggered enabling the truck 205to be searched to determine if the detected RFID tag and correspondingtooth 152 was in the bed of the truck 205. If a tooth 152 containing anRFID tag had broken/fallen off the bucket 150 and was in the truck 205,it could be found before leaving the site or being deposited in thecrusher 210. Preferably, the RFID reader 225 is positioned a far enoughdistance away from the bucket 150 that the reader 225 does not detectRFID tags in the teeth 152 that are still in place on the bucket 150.

In addition, an RFID reader 230 can be positioned before the entrance tothe crusher 210 to detect the RFID tag on a tooth 152 prior to the tooth152 entering the crusher 210 (e.g., the reader 230 could be positionedover the conveyor 215 feeding the crusher 210). Again, if the reader 230detects an RFID tag, an alarm is triggered and the conveyor 215 and/orcrusher 210 is/are stopped, enabling the tooth 152 to be located priorto entering the crusher 210.

An RFID tag in a tooth 152 can include information identifying the tooth152. For example, the RFID tag can be written with data such as, but notlimited to, a serial number, an origin, a date of manufacture, etc. Thisstored information can enable a user to quickly determine where thetooth 152 came from promoting faster repair of the bucket 150 orreturning of the tooth 152.

In some embodiments, an RFID reader 235 is included in the heavy machine100 itself (see FIG. 1). The reader 235 reads all of the RFID tagslocated on the machine 100, including the tags on the teeth 152. Acontroller or computer receives information from the reader 235 aboutthe tags detected. The controller then provides diagnostic informationto a user. This information can include when the tooth 152 wasinstalled, how many hours the tooth 152 has been in operation, etc. Inaddition, should a tooth 152 break/fall off, the controller alerts theuser of this condition enabling the lost tooth 152 to be found quicklyand replaced.

In some embodiments, additional circuitry is included with the RFID tagto determine the amount of wear of a tooth, enabling preventativemaintenance to be performed before a tooth fails.

In some embodiments, the RFID tag 300 is detuned when the tooth 152 ismounted to the bucket 150. When the tooth 152 breaks/falls off thebucket 150, the signal strength of the RFID tag 300 increases. Thereader 235 detects the increase in signal strength and determines thatthe tooth 152 has broken/fallen off the bucket 150.

FIGS. 3-5 show a view of a heavy machine bucket tooth 152. The tooth 152includes an active RFID tag 300 encased in a ceramic enclosure 305, theceramic enclosure 305 is then encased in steel 310. A separate controlcircuitry can also be included in the ceramic enclosure 305 to activatethe RFID tag 300 when the tooth 152 is shipped or installed, savingbattery power and extending the life of the RFID tag 300. The ceramicenclosure 305 with the RFID tag 300, and any other circuitry, is placedin a mold into which liquid steel is poured to form the tooth 152. Theceramic enclosure 305 protects the RFID tag 300 from the heat of theliquid steel. The RFID tag 300 is detuned such that the steel of thetooth 152 tunes the RFID tag 300 to the correct frequency, using thetooth 152 as an antenna. In some embodiments, a tuning circuit in theRFID tag 300 tunes the tag 300 once the tag 300 is activated in thetooth 152.

FIG. 6 shows another construction of a heavy machine bucket tooth 152incorporating an RFID tag 300. The tag 300 is mounted to an end 600 ofthe tooth 152. The end 600 is inserted into a mounting bracket 605 andthe tooth 152 is secured to the mounting bracket 605. In thisconstruction, the RFID tag 300 takes advantage of the metal of the tooth152 and the bracket 605, using backscattering to increase an intensityof the RFID signal.

FIG. 7 shows a construction of a heavy machine bucket tooth 152 arrangedto receive an RFID tag. The tooth 152 includes a hole 700 drilled intothe base of the tooth 152. A cylindrical RFID tag is inserted into thehole 700. In some constructions, a ceramic disk is placed over the RFIDtag, and the hole 700 is welded shut.

FIG. 8 shows a construction of a ceramic plug 800 for insertion in thetooth 152 of FIG. 7. The ceramic plug 800 encapsulates an RFID tag and atooth wear detection circuit. Four probes 805, 810, 815, 820 extend outof the ceramic plug 800. When the ceramic plug 800 is inserted into thehole 700 of the tooth 152, the probes 805-820 each contact the tooth 152and are thereby electrically coupled to the tooth 152. The weardetection circuit uses the probes 805, 810, 815, 820 to electricallytest the tooth 152 and determine the wear of the tooth 152. The weardetection circuit provides data to the RFID tag 300 regarding the wearof the tooth 152 (e.g., amount of loss, useful life remaining, etc.).The RFID tag 300 then communicates (e.g., via a wired or wirelessconnection) the wear information to an RFID reader (e.g., in a cab of ashovel, to a portable RFID reader, etc.).

FIG. 9 shows a wear detection circuit 900 used to determine wear of thetooth 152. The circuit 900 uses a four-point resistance method todetermine wear. A current source 905 produces a current that is appliedto two of the probes 805 and 820. The current flowing through the probes805 and 820 is detected by a current transducer 910. A voltagetransducer 915 of the circuit 900 detects a voltage across the other twoprobes 810 and 815. Using the detected current and voltage, amicrocontroller 920 of the circuit 900 determines a resistance of thetooth 152. The resistance varies based on the material composition ofthe tooth 152, the permittivity of the tooth 152, and the dimensions ofthe tooth 152. As the tooth 152 wears, the resistance of the tooth 152changes. The change in resistance can thus be used to determine the wearand tear on the tooth 152. In some embodiments, the initial resistance(i.e., when the tooth 152 is new) is recorded in the RFID tag 300. Also,in some embodiments, other resistance measurements (e.g., the resistancepreviously determined) are recorded in the RFID tag 300.

Various features and advantages of the invention are set forth in thefollowing claims.

What is claimed is:
 1. A system comprising: a heavy machine tooth; amounting bracket coupling the heavy machine tooth to a bucket of a heavymachine; an RFID tag positioned between the mounting bracket and theheavy machine tooth; and an RFID reader configured to receive a signalfrom the RFID tag and detect separation of the heavy machine tooth fromthe bucket based on the signal received from the RFID tag.
 2. The systemof claim 1, wherein the RFID tag is an active tag.
 3. The system ofclaim 1, wherein the signal received with the RFID reader from the RFIDtag when the heavy machine tooth is separated from the bucket isstronger than the signal received with the RFID reader from the RFID tagwhen the heavy machine tooth is coupled to the bucket.
 4. The system ofclaim 1, wherein the signal received with the RFID reader from the RFIDtag when the heavy machine tooth is separated from the bucket isdifferent than the signal received with the RFID reader from the RFIDtag when the heavy machine tooth is coupled to the bucket.
 5. The systemof claim 4, wherein a strength of the signal from the RFID tag when theheavy machine tooth is separated from the bucket is the same as a signalof the signal from the RFID tag when the heavy machine tooth is coupledto the bucket.
 6. The system of claim 1, wherein the RFID tag is mountedto an end of the heavy machine tooth and the end of the heavy machinetooth is inserted into the mounting bracket to couple the heavy machinetooth to the bucket.
 7. A system comprising: a heavy machine tooth; andan RFID tag positioned between a mounting bracket coupling the heavymachine tooth to the bucket and the heavy machine tooth, whereindetection of a signal from the RFID tag with an RFID reader indicatesseparation of the heavy machine tooth from the bucket.
 8. The system ofclaim 7, wherein the RFID tag is an active tag.
 9. The system of claim7, wherein the signal received with the RFID reader from the RFID tagwhen the heavy machine tooth is separated from the bucket is strongerthan the signal received with the RFID reader from the RFID tag when theheavy machine tooth is coupled to the bucket.
 10. The system of claim 7,wherein the signal received with the RFID reader from the RFID tag whenthe heavy machine tooth is separated from the bucket is different thanthe signal received with the RFID reader from the RFID tag when theheavy machine tooth is coupled to the bucket.
 11. The system of claim10, wherein a strength of the signal from the RFID tag when the heavymachine tooth is separated from the bucket is the same as a signal ofthe signal from the RFID tag when the heavy machine tooth is coupled tothe bucket.
 12. The system of claim 7, wherein the RFID tag is mountedto an end of the heavy machine tooth and the end of the heavy machinetooth is inserted into the mounting bracket to couple the heavy machinetooth to the bucket.
 13. A system comprising: a mounting bracketcoupling the heavy machine tooth to a bucket of a heavy machine; and anRFID tag positioned between the mounting bracket and the heavy machinetooth, wherein detection of a signal from the RFID tag with an RFIDreader indicates separation of the heavy machine tooth from the bucket.14. The system of claim 13, wherein the RFID tag is an active tag. 15.The system of claim 13, wherein the signal received with the RFID readerfrom the RFID tag when the heavy machine tooth is separated from thebucket is stronger than the signal received with the RFID reader fromthe RFID tag when the heavy machine tooth is coupled to the bucket. 16.The system of claim 13, wherein the signal received with the RFID readerfrom the RFID tag when the heavy machine tooth is separated from thebucket is different than the signal received with the RFID reader fromthe RFID tag when the heavy machine tooth is coupled to the bucket. 17.The system of claim 16, wherein a strength of the signal from the RFIDtag when the heavy machine tooth is separated from the bucket is thesame as a signal of the signal from the RFID tag when the heavy machinetooth is coupled to the bucket.
 18. The system of claim 13, wherein theRFID tag is mounted to an end of the heavy machine tooth and the end ofthe heavy machine tooth is inserted into the mounting bracket to couplethe heavy machine tooth to the bucket.